1. Start with an entry level DSLR. Although E-P1 (or Panasonic GF1) takes good photos with a small size, they are not as good in aspects like focusing speed (their strength is in small size) or high ISO noise (important for indoor photography).
2. I would recommend getting Canon 550D with its kit lens. If you should be happy with this camera, at least initially. But DSLRs are poisons, so you may want to upgrade in the future, and this is where Canon comes in (instead of recommending you a Nikon camera): when it comes to high quality lenses (that is, when you get poisoned/addicted), Canon lenses are generally cheaper, and the more expensive the lens, the more you will save with a Canon version. For example, Canon 17-55mm f/2.8 IS is about $300 cheaper than Nikon's version which does not have "IS" function (known as VR). Nikon's entry level cameras (those similar to Canon 550D in price) cannot use some important lenses without losing autofocusing ability (eg, 50mm f/1.8).
3. If you decide DSLR is not for you, then, E-P1 is the second best (or other micro-4/3 cameras). Their image quality is greatly better (5 to 10 times better) than a small DC when lighting is not the best (such as indoor photography).
